The present invention pertains generally to a vehicle-mounted object detection system and a technique for improving the information obtained from the system.
Many radar (radio detection and ranging) systems are relatively inexpensive and are feasible for mounting on personal vehicles, such as automobiles, without prohibitively increasing the price of the vehicle. For example, inexpensive radar systems are mounted on the side mirrors of some cars and are used to illuminate the vehicles"" blind spots. Other systems under development use ultrasound or optics to accomplish the same goal. Radar, however, is preferable as it is much less affected by adverse weather conditions.
One problem that arises with these detection systems pertains to receiving return signals from objects that do not need to be brought to the driver""s attention. Such objects include the road, the bumpers of the vehicle, and any other objects that are predictably present and pose no threat to the safe navigation and operation of the vehicle. The radar return from such objects degrades the ability of the system to bring dangerous objects to the attention of the driver by creating clutter on a visual display or noise on an audible feedback system. This clutter can be collectively referred to as xe2x80x9cnoisexe2x80x9d.
Efforts have been made to filter unwanted information from vehicular object detection systems. For instance, some systems use Doppler to distinguish between useful information and unwanted information. Objects with high Doppler shifts are typically passing by the vehicle quickly, such as those which are stationary relative to the ground. Objects such as other cars positioned in a blind spot exhibit little to no Doppler shift and are, therefore not detected by such systems. These objects are naturally designated as useful information to the driver. Objects having a relatively uniform surface, such as the ground, a curb, a divider or objects protruding from the vehicle carrying the radar system, also return a low Doppler shift by virtue of their smooth, continuous surfaces. Doppler-related filters, therefore, fail to exclude all unwanted information.
Other efforts pertain to excluding false return signals which are generated by radar systems mounted on other vehicles. These can be considered false returns because they are not actually xe2x80x9creturnedxe2x80x9d signals. These efforts do not address the problem of real return signals that bounce off of objects which do not need to be brought to the driver""s attention.
It would be advantageous to provide a method for communicating useful radar return signals to the driver of a vehicle without also communicating radar return signals pertaining to objects which do not need to be brought to the driver""s attention.
It would also be advantageous to provide a method of updating the criteria of which signals constitute useful information and which signals can be categorized as noise.
The present invention, therefore, relates to a system and technique or method for reducing undesirable return signals from the output of an object detection system. The technique generally comprises providing an object detection system having an output, placing the detection system in an environment free of contacts, recording a baseline noise signal, placing the system in an operating environment, and deleting any signal matching the recorded baseline from the output.
Providing an object detection system is preferably accomplished by providing a vehicular mounted radar system. It is envisioned, however, that the methods of the present invention could be embodied to apply to visual or optical detection systems, such as infrared, or acoustic detection systems such as ultrasonic detection systems. The output of the object detection system is preferably visual or audial, such as a display screen, and audible alarm or tone, or both. In the case of an audio output, the audible tones produced by the system would correspond to return signals and would preferably sound when either a turn signal in the direction of the object is activated, or when the steering wheel of the vehicle is turned toward the detected object. It is also preferable to establish a minimum amplitude threshold for a given range above which an object would cause an alarm regardless of the status of the turn signals or steering wheel of the vehicle carrying the system.
Placing the object detection system in an area free of contacts can be accomplished in a factory setting or on the road by the operator of the vehicle. Placing the object detection system in a factory setting preferably includes mounting the detection system on the intended vehicle or a similar model, and providing a flat floor suitable for simulating a road. More preferably, the area free of contacts is any given road on which the vehicle carrying the system happens to be travelling, at a time when there are no contacts within operable range of the object detection system. Insofar as the range of most object detection systems is relatively short, most roadways will be free from contacts periodically. Preferably, the system is constructed and arranged so that the driver of the vehicle carrying the object detection may initiate recording a baseline signal by pressing a button or similar action. Alternatively, it is envisioned that a baseline signal may automatically be recorded whenever the object detection system perceives the absence of contacts fitting a predetermined criteria for a period of time.
Once the object detection system is in an appropriate area free from contacts, a baseline noise signal is recorded. The baseline noise signal includes any returns the system receives on its emitted pulses. Because only signals reflected from contacts are desired, all other reflected signals can be considered noise. The noise signal may be recorded on an instant basis as a xe2x80x9csnapshotxe2x80x9d or, preferably, recorded over a predetermined period of time and averaged. This is especially advantageous when the recording is being conducted on an actual road as there are predictably more anomalies on a road than in a factory setting.
After a suitable baseline noise signal is recorded, the object detection system is ready to be used in an actual setting. It is thus placed in an operating environment. In the preferred embodiment where the baseline signal is an actual road during a period of time where there are no contacts present, the operating environment will be the same as the recorded environment, except that contacts may or may not be present. This embodiment is preferable because the baseline noise signal will more accurately represent the noise signal of the operating environment.
While in the operating environment, the signals received by the object detection which matches the baseline noise signal are not included in the output. An object detection system having a visual display would, therefore, display only those return signals that do not match, or are stronger than, the baseline signal. Similarly, an object detection system having an audio output would be prevented from emitting audible tones corresponding to those return signals that match, or are weaker than, the baseline noise signal.
In order to exclude those signals weaker than or matching the baseline noise signature, the computer or microchip of the radar system is programmed to require a stronger return for a given range than that of the baseline signal. xe2x80x9cIgnoringxe2x80x9d the baseline signal results in a radar system that presents a cleaner signal, showing only those things that are xe2x80x9cdifferentxe2x80x9d than the baseline signal. It is conceivable that this method could also be used to enhance the output of the ultrasonic and optical systems as well. It is also conceivable that this technique may have applications other than on vehicles, such as a stationary proximity sensor which provides a warning when an object gets too close to the sensor.
It is thus an object of the invention to provide a method for communicating useful radar return signals to the driver of a vehicle without also communicating radar return signals pertaining to objects which do not need to be brought to the driver""s attention.
It is also an object of the invention to provide a method of updating the criteria of which signals constitute useful information and which signals can be categorized as noise.
These and further objects and advantages of the present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.